This is a variant of my best fidget toy with diamond knurling, for those who like some more aggressive texture. Also see my other fidget rings (including a bracelet).

It's a small, but satisfying fidget toy. You'll probably not want to wear it all the day due to it's size, but it's unobtrusive enough so you can still do a lot of things while wearing it. But while wearing it, you have a fidget thing right at hand for some quick fidgeting. (I'm wearing one as I type, and fidgeting with it when I'm thinking about what to type next.)

Also the little planet gears look like plus signs - for some positive influence :) and they look quite a bit mesmerizing when moving in perfect unison.

I uploaded 5 sizes, 14mm, 16mm, 18mm, 20mm and 22mm. If you need another size, ask in the comments and there's a good chance I'll make that.

Printing: 

• 0.4mm nozzle (or lower?), 
• random seam placement,
• I use 0.17mm layer height.
• Tolerances are tight; requires a well tuned printer.

You might need to use a bit of force to break the gear loose at first, but after a bit of breaking in it is supposed to run quite smoothly.

If you can't get it free, try:

• another filament, some work better than others. Silk seems to be prone to fusing.
• reducing the extrusion multiplier (flow ratio) a bit
• or use a slightly negative value for XY size compensation (PrusaSlicer), e.g. -0.02mm,
  or a slightly negative XY contour compensation and a slightly positive XY hole compensation (OrcaSlicer).

Multocolor: 

• If you have a Bambu-style multicolor setup, try adding one or two rings and set them to “flush into object” to convert purge poop into some strange colored bonus rings - see image. Also reduce the flush volumes, I used 99 mm³, but next time I'll reduce that further.

Happy fidgeting!